Broadband ISDN(B-ISDN) was a vision in the mid-1980s for a universal communications network over which voice, data and moving image communications would be transmitted broadband and digitally. With broadband ISDN, a uniform high-speed network would be established worldwide for the various applications.
This universal network was to be able, on the one hand, to take over the functions of the then existing voice networks, data networks and television networks and, on the other hand, to provide sufficient scope for the implementation of future communications technologies. A variety of broadband services were envisioned, including video telephony, workplace and video conferencing, multimedia technology, television program distribution, and broadband cable text. Conceptually, the broadband ISDN was to be equipped with transmission speeds of up to 140 Mbit/s and was based on ISDN in the transmission hierarchy.
Standardization for this universal network was started by the International Telecommunication Union( ITU) in 1990 under the name B-ISDN. In 1988, the ITU selected ATM as the transport mechanism for B-ISDN. Embedded in the Synchronous Digital Hierarchy( SDH) transmission frames, ATM cells carry the actual user data of the various services.
B-ISDN was to use a method of "signaling channel signaling" for signaling, called meta-signaling, and the protocol for B-ISDN signaling was to be the ITU standardized protocol Q.2931 and for public wide area networks the protocol B- ISUP according to Q.2761 to Q.2764. In addition, there were proposals from the ATM Forum forsubscriber network interfaces( UNI) and network network interfaces( NNI).